Over the last few years, intentionally manipulating Earth's climate on a planetary scale has gone from a fringe idea to a possibility debated by mainstream scientists. That's worried a lot of people, and last week the practice was informally placed off-limits by 193 nations.

The moratorium, enacted under authority of the international Convention on Biological Diversity treaty won't be legally binding for at least several more years. If it goes into effect, the United States — which has signed but not ratified the treaty — won't be bound to it. It would also allow small-scale, highly controlled research.

But even informally, the moratorium has teeth. It would make anyone who wants to try geoengineering — feeding CO2-gobbling oceanic plankton with iron, pumping sunlight-blocking aerosols into the atmosphere, storing CO2 into underground rock deposits — an international pariah. And while research is technically possible, it would have to pass a regulatory gauntlet so challenging that it might as well be banned.

Not surprisingly, the moratorium is quite controversial. With each Russian heat wave or South Asian flood, and each finding that rising CO2 has historically triggered climate instability, the need for fixing the climate becomes more urgent. Without a profound and probably unlikely change in humanity's centuries-long reliance on burning fossil fuel, geoengineering could represent a last-ditch chance at averting catastrophe, or at least buying a bit more time. If nothing else, geoengineering research could help us learn more about the weather.

Supporters of a ban, however, say that climate and weather are too complex to engineer. Any intervention would have both winners and losers; what's good for China, say, might be bad for India, and vice versa. Geoengineers could make a bad situation worse, and holding out for some nick-of-time rescue just distracts attention from hard, practical energy reforms that need to start now.

People tend to focus on Darwin's ideas about natural selection, but he also spent a portion of The Origin of Species discussing another powerful evolutionary force: sexual selection.

If a species prefers to mate with members that have a specific trait—bright plumage, for example—it won't take long for that trait to sweep through the species. In the same way, having two different mating preferences in a single population can split it in two in the same way that a geographic barrier can. In both cases, geography and mate choice, the resulting reproductive isolation can ultimately lead to the evolution of new species, as each population undergoes separate genetic changes.

This week, PNAS published a paper showing that this sort of reproductive isolation can take as little as a single generation in flies, because it doesn't rely on genetic changes in the insects—it's driven by the bacteria that live on them.

This sort of reproductive isolation isn't just theory; it's been demonstrated in the lab. Fruit flies can be grown under different conditions—temperature, humidity, food source—for multiple generations, after which the flies will have a strong preference for mating with those raised under identical conditions. Even when the flies are no longer isolated, they mate as if they were.

The new experiments seemed to have started out as if they were heading in the same direction. A single population of flies was split, and separate groups were reared on two different food sources, one sugar-based, the other starch. After 25 generations, the two groups had a strong preference for mating with their peers from the same food source. So far, perfectly normal. Things started to get weird when the authors started testing earlier generations, though. The mating preference was already present at 11 generations and, shockingly, also appeared at the second generation, way too fast for a genetic change to sweep through the population.

With genetics ruled out, an environmental factor was the obvious choice, and the authors decided to look into whether bacteria in the different food sources made a difference. Treating the flies with antibiotics completely wiped out the mating preference, confirming their suspicions. So, they sampled the bacteria present in the two different populations, and found a single species, the starch-loving Lactobacillus plantarum, that was present in far higher numbers in one of the two populations. So, they treated the flies with antibiotics to get rid of the resident bacteria, and then inoculated them with L. plantarum. This created a mating preference as well.

How could a bacterial species have this effect? The authors think it's all in the pheromones flies use for mating. These are released from the fly's cuticle, where the bacteria take up residence. Their presence then alters the relative amounts of several of these pheromones, tweaking the sexual signals sent out by the flies.

The findings provide some experimental support for a relatively new idea about evolutionary selection. Since Darwin's time we've tended to assume that items under selection are the genes carried by an organism or population of organisms. But these results show that it's not just a host's genome that can undergo selection; it's the host plus everything that lives on or in it. The Hologenome Theory posits that it's the host genome plus its associated microorganisms that ends up being the unit of selection.

At this point, it's probably worth noting that every one of us carries far more copies of bacterial genomes than we do of our own, human genome.

RNA molecules aren't always faithful reproductions of the genetic instructions contained within DNA, a new study shows. The finding seems to violate a tenet of genetics so fundamental that scientists call it the central dogma: DNA letters encode information and RNA is made in DNA's likeness. The RNA then serves as a template to build proteins.

But a study of RNA in white blood cells from 27 different people shows that, on average, each person has nearly 4,000 genes in which the RNA copies contain misspellings not found in DNA.

"It's unbelievable," says Mingyao Li, a geneticist at the University of Pennsylvania Medical School in Philadelphia. Li presented the finding November 3 in Washington, D.C., at the annual meeting of the American Society of Human Genetics.

Scientists already knew that every now and then RNA letters can be chemically modified or edited — sort of the molecular equivalent of adding an umlaut to some letters. But those RNA editing events are not common.

What Li and her colleagues discovered is quite common. RNA molecules contained misspellings at 20,000 different places in the genome, with about 10,000 different misspellings occurring in two or more of the people studied. The most common of the 12 different types of misspellings was when an A in the DNA was changed to G in the RNA. That change accounted for about a third of the misspellings.

Some researchers who saw Li's presentation asked whether a virus used in growing the white blood cells that the researchers studied might be the source of the shenanigans. Li and her collaborators had wondered the same thing. In order to rule out the virus, the researchers analyzed skin cells from the same people and found that RNA misspellings originally discovered in the white blood cells were also in the skin cells. And the misspellings aren't just rare, random mistakes. "When DNA and RNA differ from each other it happens in nearly every RNA" copy, Li says.

The researchers don't yet know how the RNA misspellings happen. They could be substitutions made while the RNA copy is being made, or the changes could happen later. The consequences of the misspellings are also unknown. For instance, misspellings might cause the RNA to be degraded faster or interfere with the molecule's ability to make proteins.

Space-faring humans have called the International Space Station home for 10 years now, but the orbital laboratory only recently got a window worthy of its stunning views.

The Cupola (pronounced "kyoo-pel-ah") is a seven-paned geometric dome that boasts the biggest spacecraft window ever: a central, circular pane with a 31-inch diameter. Combined with six other trapezoidal windows, the device offers a nearly unimpeded view of space and the big blue marble zipping by 220 miles below.

Five brand new close-ups of comet 103P/Hartley 2 arrived at NASA's Jet Propulsion Lab amid cheers and applause at 8:02 Pacific time this morning.

The Deep Impact probe (now on a mission called EPOXI) passed by comet Hartley 2 at 7:01 a.m. PDT, the fifth time in history that a spacecraft has been close enough to photograph the heart of a comet. The probe flew through the comet's diffuse corona at about 27,500 miles per hour and came within 435 miles of its icy, dirty core.

Observations leading up to the flyby showed that Hartley 2 is small but active. It's only about 1.36 miles across, a shrimp compared to other comets that have been visited by spacecraft. But it spews several times more gas and dust than other comets. In this image from the moment of closest approach, the comet looks like a bowling pin or a peanut, with at least two jets streaming off toward the sun.

"It's hyperactive, small and feisty," said Don Yeomans, a senior research scientist at NASA's Jet Propulsion Lab.

Deep Impact locked its instruments and began taking pictures of the comet 18 hours before nearest approach, when it was 496,000 miles away. By the time of closest approach, it was snapping photos once every four seconds.

But astronomers had to wait almost an hour after closest approach to get the good shots. The close-ups were stored on the spacecraft because Deep Impact couldn't point its antenna toward Earth and its cameras toward the comet at the same time.

So instead of trying to fly the spacecraft directly, engineers switched Deep Impact to autopilot, or AutoNav, about 50 minutes before closest approach. In AutoNav mode, the spacecraft aims for the brightest nearby object, excluding the sun.

Models predicted that without AutoNav, there would be just a 0.1 percent chance of actually imaging the nucleus, according to EPOXI flight director Rich Rieber.

"AutoNav's prediction for the orbit of the comet was dead on," Rieber said. "Those guys did magic."

Deep Impact is the first spacecraft ever to visit two comets. Its primary mission was to make a crater on the surface of the comet Tempel 1 in July 2005, which showed scientists what that cosmic dirtball was made of. Deep Impact then spent a year observing extrasolar planets before firing its thrusters and heading toward Hartley 2.

"This is the third bonus mission we've gotten out of this," said Rick Grammier, director for solar system exploration at JPL, on NASA TV this morning.

The spacecraft still goes by the name Deep Impact, but its mission was renamed EPOXI, a mishmash of acronyms for an extrasolar planet observation mission (EPOCh) and the Deep Impact Extended Investigation (DIXI).

Hartley 2 was discovered by Australian astrophotographer Malcolm Hartley in 1986, when it showed up as a smudge on a photographic plate. Hartley was at JPL mission headquarters when the images arrived.

"It's absolutely awesome," he said. "I'm overwhelmed by everything that's happened in the past few weeks."

Hartley 2 wasn't actually NASA's first choice for the next comet encounter. The A-list comet, called 85P/Boethin, disappeared without a trace. Scientists think it may have broken up into untraceable fragments.

NASA will continue to download new data from the close encounter until Nov. 6, and Deep Impact will keep taking images for the next three weeks as it leaves the comet.

"Despite the smiles and tears that you see, our job is far from over," Rieber said. "After the next three weeks, the future life of Deep Impact is uncertain, but we have many ideas about how to use our great spacecraft."

After seven months of obliterating protons, the 17-mile-around Large Hadron Collider paused this morning to switch over to smashing lead ions (atoms of lead stripped down to their dense cores).

The goal is to recreate the energy of the universe back to just millionths of a second after the Big Bang.

"The LHC's lead-ion collisions may generate temperatures up to 500,000 times hotter than the center of the sun," Timothy Hallman, a physicist at the Science for Nuclear Physics in Washington D.C., said in a release.

Around those temperatures, quarks and gluons — the "glue" that binds quarks into protons and neutrons — are in a plasma-like state. Hallman said recreating the ultra-hot conditions with collisions between lead ions may "provide vital insight" into how the universe evolved at such a crucial time.

The LHC, situated underneath the French-Swiss border and operated by CERN, paused proton collisions around 3 a.m. EDT this morning. For the next month, physicists will collide heavy lead ions that are expected to generate roughly 10,000 particles per collision. Three cylindrical, colossal detectors hugging the LHC's beamline — known by their acronyms ALICE, ATLAS and CMS — will record the resulting particle soup.

Once the lead-ion collisions wrap up in December, engineers will perform two months of maintenance to allow the LHC to pick up in early 2011 where it left off with proton collisions today. Meanwhile, seven months' worth of proton-collision data awaits physicists hunting for shadows of the Higgs boson — the particle theorized to give matter its mass — in the energetic collisions.

"Over the last seven months, the intensity of the LHC's proton beams has increased 200,000 times," Dennis Kovar, a nuclear physicist at the U.S. Department of Energy in Washington D.C., said in a release. That collision intensity has led to double the data physicists around the world were hoping for, and could speed discovery of weird new particles including the Higgs.

"The eyes of the world might be on the hunt for the Higgs boson, but … there is a wealth of physics research being done using the LHC's proton collisions," Joseph Dehmer, director of the National Science Foundation's physics division, said in release.

The collider is not only the biggest ever built, but the most costly at an estimated $9 billion. And so far it hasn't had an easy time trying to unravel the universe's mysteries.

Shortly after engineers ramped up the LHC in September 2008, faulty wiring between two particle-corralling magnets sprung a leak in the machine's extensive liquid helium cooling system. The mishap flooded part of the subterranean tunnels with 6.6 tons of ultra-cold fluid, causing the helium to rapidly evaporated into gas and damage magnets at the leak site.

Engineers repaired the immediate damage, but unless the faulty connections are replaced, the LHC can't reach its promised particle-colliding power of seven times better than the Tevatron in Illinois (the second-most-powerful in the world). For now it's restricted to being about 3.5 times more powerful than the Tevatron.

To replace the faulty magnet-to-magnet connections, CERN plans to shut down the LHC for 16 months starting in December 2011. The window may leave an opportunity for the Tevatron to help verify, or trounce, the existence of the Higgs particle.

Images: 1) A simulation of the particle soup the ALICE detector at the LHC will see. / CERN. 2) The source of led ions held by Detlef Kuchler, a physicist in CERN's beams department. / M. Brice/CERN.

Now, before the environmentalists among you get upset, I'm not suggesting that species invasions are good things. They're not. They throw ecosystems out of whack, crowd out plants and animals we already know and love, and generally cause trouble.

But invasive species are living creatures, too. That's easy to forget amidst conservationist concerns, which can seem almost schizophrenic in treasuring some creatures (don't touch that tortoise!), while actively encouraging the extermination of others.

So for a few minutes, let's put aside our usual feelings about invasive species, and just talk about some really cool animals.